RU2797580C1 - Static reversible converter for uninterrupted ac and dc consumer supply - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention is related in particular to voltage converters designed for uninterrupted power supply to AC and DC consumers. Static reversible converter for uninterrupted power supply of AC and DC consumers contains the first input-output port on the DC side with a battery connected to it and the second input-output port on the AC side with an industrial frequency AC voltage source connected to it. The static reversible converter operates in inverter and rectifier modes, set by the control system. In inverter mode, high stabilization of the AC voltage is provided at the input-output port on the AC side, and in rectifier mode, optimal conditions for charging the battery are provided, allowing to increase its service life.

EFFECT: in a static reversible converter, optimal modes of operation of its constituent devices are provided, which makes it possible to achieve high efficiency and reliability of the static reversible converter, as well as its high output.

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Description

The invention relates to the field of electrical engineering, in particular, to static reversible converters that perform the function of uninterruptible power supplies, in which, when the main power source in the form of a power frequency AC voltage source fails, DC consumers are powered from a battery, as well as AC consumers current by converting the DC electricity stored in the battery into three-phase AC energy. During normal operation of the main AC power source, the battery is charged, as well as the supply of DC and AC consumers.

State of the art

Uninterruptible power supplies use as primary energy sources (see, for example, patent, RF, No. 2426215) an alternating voltage source and a direct current source, in the form of a battery, which is the most critical link in operation.

Today, rechargeable batteries are most widely used: nickel-hydrogen, nickel-cadmium, nickel-metal hydride, lithium-ion or lithium-polymer, differing from each other in the type of electrolyte used (see, for example, patent, RF, No. 2689887), and also acidic and alkaline (see, for example, patent, RF, No. 2729913).

To increase the service life of rechargeable batteries, the most important condition is to ensure the required charging and discharging characteristics (see D.A. Khrustalev. Accumulators. Moscow, 2003) in the range of permissible current and voltage values.

In uninterruptible power devices, three-phase AC voltage sources of industrial frequency are mainly used to supply high-power consumers (see, for example, patent, RF, No. 2426215), while, in order to reduce weight and dimensions, a battery with a lower voltage is used to the voltage of the power frequency alternating voltage source. It should be noted that the so-called low-maintenance lead-acid batteries are most widely used for these purposes in the energy industry, which are highly reliable and unpretentious in operation, and also provide long service life in buffer mode - 20 years or more (see, for example, " Comparison of different types of batteries". On the website: http://ess-asimut.ru/upload/iblock/4a9/4a9febfa61b389513f277fc7b0d6b32f.pdf).

Today, switching converters use the main components in the form of chokes, capacitors, switches with low resistance in the closed state and low-loss transformers. The efficiency η of these devices is at least 0.8 and can reach 0.9 or more (see Switching voltage regulators. On the website: https://studfile.net/preview/6445693/). In modern switching converters, insulated gate field effect transistors (MOSFETs), as well as high-voltage high-speed power insulated gate bipolar transistors (IGBTs), operating in a key mode, which allow high power and high efficiency of the converter, which are controlled by a pulse-width signal, are widely used. (PWM) via a driver from the microcontroller (see, for example, "IGBT transistors" on the website: https://drives.ru/stati/modul-igbt/; patents, RF: No. 2513547, No. 2481691). It should be noted that completely domestic IGBT modules that can be used to implement pulse converters are listed on the website: https://www.angstrem.ru/company/articles/silovaya_ekb_lineykajpolnostyu_otechestvermykh_igbt_moduley/).

A multi-channel stabilizing uninterruptible power supply device is known (patent, RF, No. 2221320), containing a mains rectifier with AC input terminals and DC output terminals that are connected to the input power terminals of the charge-buffer converter, the output terminals of which are connected to a backup battery and the first input terminals of DC voltage converters according to the number of output voltage channels.

The disadvantage of this device is that it does not provide the ability to recuperate the energy of the battery in the AC supply network.

Known static reversible converter for powering consumers of AC and DC (see patent, RF, No. 2513547), which is closest to the proposed invention and taken by the authors as a prototype. This prototype of a static reversible converter for powering AC and DC consumers includes a first input-output port on the DC side with a battery connected to it and a second input-output port on the AC side, for electrical connection of ports between they include a high-frequency link and a link of an autonomous industrial frequency inverter, connected in series with each other, and both links are used in inverter and rectifier modes, while in the inverter mode of operation of the reversible converter, the input DC power is supplied to the first port, and the AC output is removed from the second port, and in the rectifier mode of the reversible converter, the input AC power is supplied to the second port, and the DC output is taken from the first port, and the high frequency link is made on the basis of single-phase bridge circuits of inverters connected to the control system, and the output AC voltage is formed using three-phase bridge circuits with output LC filters, while the high-frequency link is made for the inverter mode of operation of the converter in the form of a combined circuit of resonant unregulated inverters and voltage inverters with rectifiers connected in parallel at the input and in series at the output, and for the rectifier mode of operation converter, it is made in the form of a combined circuit of series-connected voltage inverters at the input and parallel rectifiers at the output.

The disadvantage of the prototype is that in the rectifier mode, three high-frequency links representing constant voltage sources, and having a spread in output voltage values, are interconnected by outputs, as a result of which they are equalized due to short-circuit currents limited by the internal resistance of these voltage sources , thereby reducing the efficiency and reliability of their work, as well as the efficiency η (η is the ratio of the power delivered at the output of the system to the power consumed at the input) of a static reversible converter for uninterrupted power supply of AC and DC consumers (hereinafter - static reversible converter).

In addition, the prototype does not meet the conditions for ensuring the required optimal conditions for charging the battery, which reduces its service life and, in general, the efficiency and reliability of the static reversible converter.

The aim of the invention is to improve the efficiency and reliability of the static reversible converter.

Disclosure of invention

The essence of the proposed static reversible converter is to provide a stable voltage in the inverter mode at the "input-output" port on the AC side using a charging converter connected between the battery and the "input-output" of the first of two high-frequency links connected in series through transformer, and when charging the battery in rectifier mode, the required algorithms for its charge are provided with optimal constant charging current and constant voltage. In addition, the DC voltage converter device connected between the “output-input” of the second high-frequency link and the “input-output” of the industrial frequency inverter achieves the required constant voltages in the rectifying mode of operation at the “output-input” of the second high-frequency link, while , optimal conditions are created for the mode of operation of high-frequency links and the choice of the transformation ratio of the transformer included between them.

Note - the symbol "input-output" in the device means that in the inverted mode it is an input, in the rectifying mode it is an output, and the symbol "output-input" in the device means that in the inverted mode it is an output, in the rectifying mode - entrance.

The static reversible converter includes a "in-out" port on the DC side, a battery, DC consumers, an "in-out" port on the AC side, a power frequency AC voltage source, AC consumers, two links connected in series through a transformer high frequency, power frequency inverter with a capacitor at the "input-output" and LC filters at the "output-input".

Introduction to the static reversible converter of a charging-converting device connected between the battery and the "input-output" of the first high-frequency link, as well as a DC voltage converter device connected between the "output-input" of the second high-frequency link and the "input-output" of the inverter industrial frequency allows you to increase the efficiency and reliability of the static reversible converter.

By turning on the charging-converting device between the battery and the “input-output” of the first high-frequency link, in the inverter mode of operation of the static reversible converter, stabilization of the battery’s variable voltages at the “input-output” of the first high-frequency link in the inverter mode, while in the rectifier mode in the mode of operation of the static reversible converter based on signals from the battery voltage and charging current sensors without breaking the circuit using a Hall sensor, the charging-converting device provides, by PWM control signals, the formation of the required algorithms for charging the battery with a constant optimal charging current and constant voltage. As a result, the resource and reliability of the battery is increased.

By connecting between the “output-input” of the second high-frequency link and the “input-output” of the industrial frequency inverter of a DC voltage converter device, which provides a voltage boost according to the booster circuit in the rectifier mode of the static reversible converter, and in the inverter mode it operates in the key mode through an open transistor, control of the diagonals of the inverter bridge of high-frequency links by a PWM pulse sequence with an optimal duty cycle D is ensured, as a result of which high stability of the generated voltages at their outputs is ensured.

The choice of the increase and conversion factors of the charging-converting device, as well as the increase factor in the DC voltage converter, provides optimal conditions for choosing the conversion factors of high-frequency links and the transformation ratio of the transformer.

Graphic illustrations

In FIG. 1 shows a general block diagram of a static reversible converter for uninterruptible power supply of AC and DC consumers, containing components with positions indicated by numbers:

1 - AB (battery);

1-1 - port "input output" on the DC side;

2 - direct current consumers;

3 - the first high frequency link;

3-1, 3-2, 3-3, 3-4 - transistor switches of the high frequency link;

3-5, 3-6, 3-7, 3-8 - high frequency link diodes;

4 - the second high frequency link;

5 - transformer;

6 - UPPN (DC converter device);

6-1, 6-2 - respectively, the first and second transistors UPPN;

6-3 - UPPN diode;

6-4 - choke UPPN;

7, 8 - respectively the first and second capacitor;

9 - industrial frequency inverter;

10 - LC filter;

11 - source of alternating voltage of industrial frequency;

11-1 - port "input output" on the AC side;

12 - AC consumers;

13 - control system;

14 - ZPU (charging-converting device);

14-1, 14-9 - respectively, the first and second diode ZPU;

14-2, 14-3 - respectively the first and second transistor ZPU;

14-4 - throttle ZPU;

14-5, 14-6 - respectively the first and second capacitor ZPU;

14-7 - DTX (current sensor without breaking the circuit using a Hall sensor);

14-8 - DN (voltage sensor);

15 ₁ - high-frequency voltage converter.

In FIG. 2 shows typical characteristics of the charging process of a lead-acid battery with a nominal voltage of 2V.

In FIG. 3 shows a block diagram of a static reversible converter for uninterruptible power supply of AC and DC consumers, containing components with the positions indicated by numbers shown in FIG. 1 and also:

15 ₂ ... 15 _n - a group of HPV (high-frequency voltage converters).

In the group 15 ₁ …l5 _n the number n≥2.

Implementation of the invention

A static reversible converter for uninterrupted power supply of AC and DC consumers includes an "input output" port on the DC side 1-1 to which a battery 1 and DC consumers 2 are connected; port "input-output" on the side of the alternating current 11-1, which is connected to the source of alternating voltage of industrial frequency 11 and consumers of alternating current 12; two high-frequency links 3, 4 connected in series through a transformer 5 with identical construction schemes, a power frequency inverter 9 with a capacitor 8 connected in parallel to the “input-output” and with LC-filters 10 connected to its “outputs-inputs” with one output, the second the outputs of which are connected to the input-output port on the AC side 11-1, in addition, the control system 13 is connected to the high frequency links 3, 4 and the power frequency inverter 9.

1. In the device (Fig. 1), a charging-converting device 14 is additionally introduced, connected between the battery 1 and the "input-output" of the high-frequency link 3, as well as the DC voltage converter device 6 with a capacitor 7 connected in parallel to its "input- output" connected in parallel with the "output-input" of the second high-frequency link 4, while the "output-input" of the DC/DC converter device 6 is connected in parallel with the "input-output" of the industrial frequency inverter 9 and contains a choke 6-4, keys, respectively, on the first 6-1 and second 6-2 transistors, the diode 6-3, and one output of the inductor 6-4 is the positive "output-input" bus of the DC voltage converter device 6, and the second is connected to the first outputs of the keys, respectively, on the first 6-1 and the second 6-2 transistors and the anode of the diode 6-3, the cathode of which is connected to the second output of the key on the second transistor 6-2 and is the positive input-output bus of the DC/DC converter device 6, and the second output of the key on the first transistor 6-1 is connected to the negative power bus of the DC/DC converter device 6; charging-converting device 14, contains a voltage sensor 14-8, a current sensor without breaking the circuit using a Hall sensor 14-7, respectively, the first 14-1 and the second diode 14-9, respectively, the first 14-2 and the second 14-3 transistor, inductor 14-4, respectively, the first 14-5 and the second 14-6 capacitor, and the first capacitor 14-5 and the voltage sensor 14-8 are connected in parallel with the “input-output” of the charger-converter 14 with two outputs, and the third output voltage sensor 14-8 is connected to the control system 13, the current sensor without breaking the circuit using a Hall sensor 14-7 is galvanically isolated in a galvanically isolated way connected to the wire going to the positive terminal of the battery 1, and the output is connected to the control system 13, the throttle 14-4 one output is connected to the positive input-output bus of the charger-converter 14, and the second output is connected to the first outputs of the keys, respectively, on the first 14-2 and second 14-3 transistors, the anode of the first diode 14-1 and the cathode of the second diode 14-9, the anode of which, as well as the second output of the key on the second transistor 14-3 and the first output of the second capacitor 14-6 are connected to the negative power bus of the charger-converter 14, the cathode of the first diode 14-1, the second output of the key on the first transistor 14-2 and the second terminal of the second capacitor 14-6 are connected to the positive bus of the charger-converter 14; high-frequency voltage converter 15 ₁ containing identical high-frequency links 3, 4, which contain a transistor bridge on transistors 3-1, 3-2, 3-3, 3-4 with diodes 3-5 connected in parallel to them in the opposite direction , 3-6, 3-7, 3-8, and the output of the series-connected transistors 3-1 and 3-2 is connected to one output of the primary winding of the transformer 5, and the output of the series-connected transistors 3-3 and 3-4 is connected to the second output the primary winding of the transformer 5, the second terminals of the transistors 3-1 and 3-3 are connected to the positive bus, the second terminals of the transistors 3-2 and 3-4 are connected to the negative power bus of the high-frequency link 3, while the "input-output" of the high-frequency voltage converter 15 ₁ is the "input-output" of the high-frequency section 3, and the "output-input" of the voltage converter 15 ₁ is the "output-input" of the high-frequency section 4; the control system 13 is connected to the charging-converting device 14 and the DC voltage converter device 6.

2. In FIG. Figure 3 shows a block diagram of a static reversible converter for uninterrupted power supply of AC and DC consumers according to figure 1 with a group of high-frequency voltage converters VPN 15 ₂ ... 15 _n connected in parallel to a high-frequency voltage converter VPN 15 _1. The number n in the group of high-frequency voltage converters VPN 15 ₁ …l5 _n : n≥2.

Description of the operation of a static reversible converter

1. Description of the block diagram of the static reversible converter according to figure 1.

As a source of alternating voltage of industrial frequency 11 can be an industrial network or a generator.

In the inverter mode of the converter, DC is supplied to the "in/out" port on the DC side 1-1, and AC output is taken from the "in/out" port on the AC side 11-1. In rectifier mode, the AC input power is supplied to the "in/out" port on the AC side 11-1, and the DC output is taken from the "in/out" port on the DC side 1-1 to charge battery 1. To battery 1 DC consumers are connected through the input-output port on the DC side 1-1, and AC consumers 12 are connected to the power frequency AC voltage source 11 through the input-output port on the AC side 11-1. As was presented above, today, industrial acid batteries are mainly used, so when describing the proposed application, as an example, we will use a lead-acid battery (battery 1) and a three-phase voltage source (commercial frequency AC voltage source 11) with characteristics, given in the prototype, namely:

change in voltage of the battery 1 from discharged to charged state is in the range from 175 to 320 V;

power frequency alternating voltage source 11 - three-phase with an alternating voltage of 380 V.

From the typical characteristics of the charging process of a lead-acid battery (see Algorithms for charging lead-acid batteries. On the website: https://www.drive2.ru/1/490695822753661142/), presented in Fig. 2, it is obvious that in order to provide the required conditions for charging the storage battery 1, at least two sensors are required - this is an output voltage sensor and an output current sensor. In this case, the algorithm for the process of charging the battery 1 should be as follows:

at the beginning, with a discharged battery 1, the necessary charge to a given (maximum) voltage must be provided by direct current (maintaining an optimal constant current);

then, when the predetermined (maximum) voltage on the battery 1 is reached, it must be charged with a constant voltage (maintaining a predetermined constant stabilized voltage).

The optimal value of the charge current (I _{charged opt.} ) for almost all types of batteries should be (see, for example, patent, RF, No. 2702758) approximately 0.1 of the nominal capacity of the battery (N.E.) and not exceed 0, 3 rated battery capacity (N.U.). Currents less than 0.1 of the nominal capacity of the battery (N.E.) also provide its charge, while it should be borne in mind that charging with a current below the lower threshold (approximately 0.03 of the nominal capacity) practically does not increase the capacity of the battery.

Therefore, in the rectifier mode, the following conditions must be ensured:

Where

U _vh.zpu - constant voltage at the "output-input" of the charging-converting device 14;

U _accum.max - the maximum voltage of a charged battery;

To implement the inverter mode of operation of the static reversible converter, the control system SU 13 sets the transistor-diode modules of the first high-frequency link 3 to the inverter mode of operation, and the transistor-diode modules of the second high-frequency link 4 to the rectifier mode of operation (through the diode rectifier bridge, while the transistors are closed ), and also sets the inverter mode of operation of the industrial frequency inverter 9. In addition, the control system SU 13 sets the charging-converting device ZPU 14 to the step-up voltage mode, and the DC voltage converter device UPPN 6 - to the key mode through the permanently open second transistor UPPN 6 -2.

To implement the rectifying mode of operation of the static reversible converter, the control system SU 13 sets the transistor-diode modules of the first high-frequency link 3 to the rectifying mode of operation (through the diode rectifier bridge, while the transistors are closed), and to the transistor-diode modules of the second high-frequency link 4 inverter mode operation, and also sets the rectifier mode of operation of the power frequency inverter 9 (through diodes, while the transistors are closed). In addition, the system SU 13 sets the charging-converting device ZPU 14 to the mode of charging current and charging voltage for the battery 1, providing the charge of the battery 1 with an optimal stabilized current and stabilized voltage, and the device of the DC voltage converter UPPN 6 sets it to the step-up DC voltage mode .

Consider the inverter mode of a static reversible converter. In this mode, the bridge circuit of the first link of high frequency 3 (typical high frequencies are above 20 kHz, in fact, in the range from 40 to 100 kHz), made on the basis of a single-phase inverter, operates in inverter mode (the output AC voltage does not exceed the supply voltage), while , the second link of the high frequency 4 operates in rectifier mode.

The construction schemes of the first high frequency link 3 and the second high frequency link 4 are identical.

The description of the operation of the first link of the high frequency 3 in the inverter mode is presented, for example: 1. "Bridge converter with PWM". Website: https://power-electronics.info/full-bridge.html. 2. Patent, RF, No. 2689401).

By controlling the PWM signal generated by the control system SU 13, the diagonal of the upper transistor 3-1 and the lower transistor 3-4 of the bridge are synchronously switched, then after a certain pause (to prevent through currents), on the contrary, the lower transistor 3-2 and the upper transistor 3 are switched on simultaneously -3 bridges, then pause again and the process repeats again. In this case, the duration of the synchronous switching on of the keys, which determines the output voltage, changes in accordance with the duty cycle D in a pulse sequence with PWM. The fill factor D is described by the following expression:

Where

τ _imp - pulse duration in a pulse sequence with PWM;

T - the period of repetition of pulses in a pulse sequence with PWM.

Diodes 3-5, 3-6, 3-7, 3-8, conducting current in the opposite direction, are connected in parallel with transistors 3-1, 3-2, 3-3, 3-4. Thanks to the reverse diodes, the voltage on the closed keys cannot exceed the voltage of the power source and, in addition, a current flows through the reverse diodes of the keys at the pause stage, “stored” in the parasitic leakage inductance of the primary winding of the transformer 5.

The generated alternating voltage by the first link of high frequency 3 from its "output-input" through the transformer 5 with a given transformation ratio K _tr , determined by the ratio of the number of turns on the secondary winding to the number of turns on the primary winding, through the rectifier of the second link of high frequency 4 enters the "input -output" of the device of the DC voltage converter 6 with the filtering first capacitor 7 connected in parallel to it. In the rectifying mode of the second high-frequency link 4, its transistors are closed and only the diode rectifier bridge works (see, for example, "Transformers, rectifiers, filters". On website: https://www.radioradar.net/hand_book/documentation/tran.html).

The conversion coefficients of the first 3 (K _pr.1 ) and the second 4 (K _pr.2 ) high-frequency links in the inverter mode are the ratio of the output rectified DC voltage of the inverter to its supply voltage (U _pit ) and correspond, without taking into account the transformation ratio of the transformer 5 K _tr approximately equal to 0.9•U _pit (taking into account the voltage drops on the open diagonal keys of the inverter and the diodes of the rectifier diode bridge, and also taking into account pulse shifts in the PWM signal to eliminate through currents and work on a transformer load). Therefore, taking into account the reversibility in the operation of high-frequency links 3, 4, the conversion coefficients of the first 3 (K _pr.1 ) and second 4 (K _pr.2 ) high-frequency links operating in the inverter mode should be chosen approximately equal and close to the value 0, 9U _pit with a margin for a stabilizing change in the duty cycle D of the PWM signal, while the transformation ratio of the transformer 5 K _tr should be chosen close to 1 (to equalize the high frequency links 3, 4 in terms of power), which is the optimal conditions for the operation of high frequency links 3 , 4.

Those. when choosing the optimal values K _pr.1 , K _pr.2 , K _tr , the following conditions must be met:

When applying a constant voltage that varies over a wide range, from the output of the battery 1 directly to the "input-output" of the first high-frequency link 3, operating in inverter mode, the duty cycle D of the PWM signals that control the opening and closing of the diagonal bridges must change over a wide range , which negatively affects the stabilization of the generated output stabilized voltage.

To stabilize the voltage at the "input-output" of the first link of the high frequency 3, associated with a change in the voltage on the battery 1, in the proposed device between the battery 1 and the first link of the high frequency 3, the charging-converting device ZPU 14 is switched on, operating in the inverter mode of the static reversible booster voltage converter with a high efficiency η, which reaches more than 90% contribute/power/kak-rabotajt-impul-snye-preobrazovateli-naprazenia-27-shem.html). As a result, high voltage stability is ensured at the “output-input” of the first high-frequency link 3 and, accordingly, at the “input-output” port on the AC side 11-1.

Consider the operation of the charging-converting device ZPU 14 in the inverter and rectifier modes of the static reversible converter.

In the inverter mode, the key on the first transistor ZPU 14-2 is closed, and the key on the second transistor ZPU 14-3 is controlled by a PWM signal generated by the control system SU 13. When the key on the second transistor ZPU 14-3 is open, the current from the battery 1 flows through the throttle ZPU 14-4, storing energy in it. The first diode ZPU 14-1 at the same time cuts off (blocks) the second capacitor 14-6 and does not allow it to be discharged through a closed key on the second transistor ZPU 14-3. The current to the load (to the "input-output" of the first link of the high frequency 3) in this period of time comes only from the second capacitor ZPU 14-6. Further, when the key on the second transistor ZPU 14-3 is closed, the electromotive force of self-induction of the throttle ZPU 14-4 is added to the output voltage on the second capacitor 14-6 and the current energy of the throttle ZPU 14-4 is given to the load. In this case, the output voltage of the ZPU 14 is greater than its input by the value determined by the inductance of the inductor of the ZPU 14-4 and the duty cycle of the PWM signal controlled by the key of the second transistor of the ZPU 14-3.

At the "output-input" of the charging-converting device ZPU 14, a stabilized voltage U _st.1 is formed:

where To _p.n.1 - the voltage increase factor ZPU 14 in the inverter mode (the ratio of the voltage at the "output-input" ZPU 14 to the voltage at the "input-output" ZPU 14).

When choosing U _st.1 and, accordingly, K _p.n.1 , one should take into account the provision of a "normal" mode of operation of the booster circuit in ZPU 14, which consists in the fact that in the step-up voltage mode according to the booster circuit, the fill factor D is selected no more 0.8 ... 0.9, and the voltage increase coefficient K _p.n. for the highest voltage options - no more than 5 (see, for example, "Calculation of the choke of the DC DC converter booster circuit". On the website: https://skachatvs.com/2000125250/raschet-drosselya-bustemoy-schemy-dc-dc-reobrazovatelya ).

In the rectifying mode of the charging-converting device ZPU 14, the key of the second transistor ZPU 14-3 is closed, and the key of the first transistor ZPU 14-2 operates in the PWM signal control mode, which is generated by the signals of the current sensor without breaking the circuit using the Hall sensor DTX 14-7 , as well as the voltage sensor DN 14-8, entering the control system SU 13, providing the required conditions for charging the battery 1 in the charging current mode and in the charging voltage mode. When a pulse is received from the control system SU 13, the key on the first transistor ZPU 14-2 opens, the current through it flows through the smoothing choke ZPU 14-4 into the first capacitor ZPU 14-5, while energy is accumulated in the choke ZPU 14-4. When the control pulse is removed from the key on the first transistor ZPU 14-2, it closes, and in the circuit: the second diode ZPU 14-9 - the throttle ZPU 14-4 - the first capacitor ZPU 14-5 starts to flow current caused by the release of the accumulated in the throttle ZPU 14-4 energy into the first capacitor ZPU 14-5. Then the cycle repeats (a step-down chopper circuit is implemented). Inductor ZPU 14-4 and the first capacitor ZPU 14-5 represent an L-shaped circuit of the LC filter.

When implementing a digital version of the voltage control method with a key on the first transistor ZPU 14-2 using only a voltage sensor DN 14-8 in real operating conditions, the battery 1 is not enough, because when the charge is turned on and off, depending on the voltage on the battery 1, its chronic undercharging and premature failure may occur. To eliminate this, in accordance with the typical characteristics of the charging process (see, Algorithms for charging lead-acid batteries. On the website: https://www.drive2.ru/1/490695822753661142/) of a lead-acid battery, shown in Fig. 2, it is obvious that a current sensor and a voltage sensor are required at the output of the ZPU 14 (see, for example, "Sensors for measuring current and voltage for automation systems". On the website: https://isup.ru/articles/16/1195/) . As a current sensor, it is advisable to use a current sensor without breaking the circuit using a Hall sensor DTX 14-7 (for example, developed and manufactured by the applicant of this invention JSC "NIIEM": DTX-100 PIGN.411521.007TU), which is "put on" through the hole in it to the wire going to the positive terminal of the battery 1. This ensures complete galvanic isolation that does not reduce the efficiency η of the static reversible converter. The output signal of the current sensor ДТХ 14-7 is fed to the output current control input, and the voltage sensor DN 14-8 - to the output voltage control input of the microcontroller in the control system SU 13, which generates a PWM signal to stabilize the charging current and voltage when charging battery 1.

As a result, the following required algorithm for the process of charging the battery 1 is provided (in accordance with the one shown in Fig. 2):

first, when the battery 1 is discharged, it is charged to the maximum voltage by direct current (stage 1, Fig. 2), i.e. maintenance of optimal direct current is ensured (see expression 2);

then, when the maximum voltage on the storage battery 1 is reached, its charge is provided by a constant voltage (stage 2, Fig. 2). From this moment, the charge current begins to fall and reaches a value that compensates for the self-discharge of the battery, i.e. the battery charge goes into buffer mode (stage 3, Fig. 2), in which the voltage is limited at the level of "floating" charge. At the same time, in order to ensure these conditions for charging the battery 1, a voltage U _st .

where K _p.n.2 is the conversion factor of the ZPU 14 in the rectifying mode of operation of the reversible static converter (the ratio of the voltage of the "input-output of the ZPU 14 to the voltage of the "output-input" of the ZPU 1).

Taking into account the reversibility in the operation of a static reversible converter, a rational choice in the inverter and rectifier modes of operation of the ZPU 14 charger-converter (see, for example, "DC / DC converters: principles of operation and unique solutions Maxim Integrated". On the website: https:/ /www.compel.ru/lib/134297) is to ensure the approximate equality of voltages U _st.1 and U _st.2 , i.e.:

The power frequency inverter 9, as in the prototype, is made according to a three-phase bridge circuit based on IGBT-type transistor-diode modules (see, for example, "Power circuit of a three-phase voltage inverter". On the website: https://helpiks.org/ 9-64571.html).

It is made reversible, i.e. operates in inverter and rectifier modes on commands from the control system SU 13. As in the prototype, the power frequency inverter 9 works in conjunction with the second capacitor 8 and LC filters 10.

It is known (see, for example, "Three-phase voltage inverters". On the website: https://ozlib.com/849786/tehnika/trehfaznye_invertory_napryazheniya) that the ratio of the input DC voltage U _p1 (at the "input-output" of the power frequency inverter 9) and variable output linear voltage U _l in a three-phase inverter in inverter mode is described by the expression:

At the same time, the ratio of the AC linear voltage U _l and the output DC voltage U _p2 (at the "input-output" of the power frequency inverter 9) in a three-phase inverter in the rectifier mode is described by the expression (see, for example, "Three-phase bridge rectifier".

• On the website: https://studref.com/601497/tehnika/trehfaznyy_mostovoy_vypryamitel):

From expressions (8, 9) it can be seen that the voltage values in the inverter U _p1 and rectifier U _p2 modes at the "input-output" of the industrial frequency inverter 9 are different. However, the excess of U _p2 over U _p1 is insufficient to equalize the voltages at the "input-output" of the high-frequency link 3 in the inverter and rectifier modes and, accordingly, to ensure the required process of charging the battery 1.

To ensure the alignment of voltages at the "input-output" of the first high-frequency link 3 and, accordingly, the rational mode of operation of the charging-converting device ZPU 14, as well as to ensure the selected optimal modes of operation of high-frequency links 3, 4 in inverter and rectifier modes, between the "output - "input" of the second high-frequency link 4 and "input-output" of the industrial frequency inverter 9 turns on the DC voltage converter device UPPN 6, which in the rectifying mode of the static reversible converter increases the voltage according to the booster circuit, and in the inverter mode, operating in the key mode through the permanently open second transistor UPPN 6-2.

Consider the operation of the DC voltage converter device UPPN 6.

In the inverter mode, the first transistor UPPN 6-1 is permanently closed, and the second transistor UPPN 6-2 is permanently open for current to flow from the “output-input” of the second high-frequency link 4 to the “input-output” of the industrial frequency inverter 9.

In the rectifying mode, the second transistor UPPN 6-2 is constantly closed, and the first transistor UPPN 6-1 operates in the control mode of the PWM signal generated in the control system SU 13.

When the key on the first transistor UPPN 6-1 is open, the current from the "input-output" of the power frequency inverter 9 flows through the inductor UPPN 6-4, storing energy in it. The diode UPPN 6-3, at the same time, cuts off the first capacitor 7 and does not allow it to be discharged through a closed key on the first transistor UPPN 6-1. The current to the load (to the “output-input” of the second high-frequency link 4) during this period of time comes only from the first capacitor 7. Further, when the key on the first transistor UPPN 6-1 closes, the electromotive force of self-induction of the UPPN 6-4 choke is added to output voltage on the first capacitor 7 and the current energy of the inductor UPPN 6-4 is given to the load. In this case, the output voltage of the UPPN 6 turns out to be greater than its input by an amount determined by the inductance of the UPPN 6-4 inductor and the duty cycle D of the PWM signal that controls the key of the first UPPN transistor 6-1. At the "input-output" of the UPPN 6, a stabilized voltage U _st.3 is formed:

where K _p.n.3 is the increase factor of the UPPN 6, equal to the ratio of the voltage value at the "input-output" of the UPPN 6 to the ratio of the voltage value at the "output-input" of the UPPN 6.

In accordance with the expressions (4, 8, 9, 10) and taking into account the reversibility in the operation of high-frequency links 3, 4, the conversion coefficients of the first 3 (K _pr.1 ) and second 4 (K _pr.2 ) high-frequency links operating in inverter mode, are selected approximately equal, then (we neglect the low voltage of the public key of the second transistor UPPN 6-2):

From expression (11) we find the transformation ratio K _tr of the transformer 5 and the coefficient K _{p.n. 3} :

As an example of the operation of a static reversible converter, consider the choice of two optimal modes of operation of high-frequency links 3, 4, taking into account the conditions in expression (4).

The first mode: K _PR =0.8; K _tr \u003d 1.

Then, in accordance with expressions (11):

U _st \u003d 1.53U _l .

At U _l \u003d 380 V we get. U _st \u003d 581.4 V.

In accordance with expressions (5, 7) K _a.s. =3.3…1.8.

In accordance with expression (13) K _{p.n. 3} = 1.353.

The second mode: K _CR =0.7; K _tr \u003d 1.2.

Then, in accordance with expressions (11): U _article =1,458U _l .

At U _l \u003d 380 V we get. U _st \u003d 554 V.

In accordance with expressions (5, 7) K _a.s. =3.2…1.5.

In accordance with expression (13) K _{p.n. 3} = 1.77.

The analysis of the above two modes shows that in the first and second modes of operation of high-frequency links 3, 4, the coefficients K _a.s. and K _p.n.3 correspond to the "normal" mode of operation. In addition, given as an example of the data of the battery 1 and AC power frequency 11, K _p. in ZPU 14 and K _a.p.

Change K _Ph.D. in ZPU 14 and K _p.n.3 in UPPN 6 conditions are created for choosing K _pr and K _tr in the optimal range.

As electronic keys on transistors and diodes in high-frequency links 3, 4, in the charging-converting device ZPU 14 and in the DC voltage converter device UPPN 6, you can use, for example, a powerful high-voltage half-bridge on an insulated gate bipolar transistor (IGBT), for example , SEMiX453GB12E4s.

As microcontrollers that generate PWM signals in the control system SU 13, you can use, for example, the ST10F276Z5T3 microcontroller.

2. Description of the block diagram of the static reversible converter of FIG. 3.

In parallel-connected, identical in circuit design, connected in series through a transformer 5, two high-frequency links 3, 4, with the same voltage conversion coefficients K _pr and the same transformation coefficients K _tr , at the points of parallel connection of these links, equalized voltages are created that practically do not cause short-circuit currents circuits that adversely affect the efficiency and reliability of the high-frequency voltage converter VPN 15 ₁ containing these high-frequency links 3, 4. As a result, conditions are provided for turning on, instead of one high-frequency voltage converter VPN 15 ₁ , a group of high-frequency voltage converters VPN connected in parallel 15 ₁ , 15 ₂ …15 _n (n≥2).

This parallel connection of a group of high-frequency voltage converters VPN 15 ₁ , 15 ₂ ...15 _n allows you to increase the power of the high-frequency voltage converter, as well as to ensure the choice of transformer 5 with a lower power.

Thus, the static reversible converter proposed in the application has the following advantages:

provides high stabilization of the AC voltage at the input-output port on the AC side;

optimal battery charging mode is provided, which increases its service life;

optimal modes of operation of the constituent devices of the static reversible converter are provided, allowing to achieve high efficiency and reliability of its operation;

the choice of conversion factors of the charging-converting device and the DC voltage converter, conditions are provided for the optimal choice of the transformation ratio of the transformer and the conversion factors of high-frequency links;

high efficiency and reliability of the static reversible converter is ensured, in view of the absence of short-circuit currents for equalizing voltages when high-frequency voltage converters are connected in parallel;

provides a high efficiency.

Claims (2)

1. Static reversible converter for uninterrupted power supply of AC and DC consumers, containing the first input-output port on the DC side with a battery connected to it and the second input-output port on the AC side with an AC source connected to it power frequency voltage, as well as a high-frequency voltage converter containing the first and second high-frequency links in the form of two bridge circuits connected in series through a transformer, made on the basis of identical single-phase inverters connected to the control system and a power frequency inverter with an input filter, moreover the first and second high frequency links, as well as the power frequency inverter are used in inverter and rectifier modes, while in the inverter mode of the static reversible converter, the DC input power is supplied to the first port, and the AC output is taken from the second port, and in the rectifier mode in static reversible converter mode, AC input power is supplied to the second port, and DC output is taken from the first port; the output AC voltage is generated using a power frequency inverter, made in the form of a three-phase bridge circuit connected to the control system and through LC filters with a power frequency AC voltage source, characterized in that an additional charger-converter connected between the first port " input-output" on the DC side and the first high-frequency link, connected to the control system and providing, in the inverter mode of operation of the static reversible converter, stabilization of the variable voltages of the battery at the input of the first high-frequency link, while in the rectifier mode of operation of the static reversible converter, signals from the battery voltage and charging current sensors without breaking the circuit using a Hall sensor, the charging-converting device provides the formation of the required algorithms for charging the battery with a constant optimal current and constant voltage, in addition, between the output of the second high-frequency link and the inverter industrial frequency, a DC voltage converter device is included, which provides an increase in voltage according to the booster circuit in the rectifier mode of a static reversible converter, and in the inverter mode it works in a key mode through an open transistor. 2. Static reversible converter according to claim 1, characterized in that n, where n≥1, additional identical high-frequency voltage converters connected in parallel to the high-frequency voltage converter are introduced.

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